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Ecology midterm 2 > Ecological interactions > Flashcards

Ecological interactions Flashcards

1
Q

The physical place where an organism lives

A

habitat

ex. tropical forest, grasslands

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2
Q

niche

A

how an organism makes its living

ex.carnivore-hunts at dusk versus daylight

herbivores- feeds on woolly plants vs grasses

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3
Q

Competition has —- and —- competition.

A

interspecific and intraspecific (within)

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4
Q

Leibig’s Law of the Minimum

A

pop. numbers can be regulated by a single resource that has the greatest relative scarcity

ex.phytoplankton has limited iron and nitrogen

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5
Q

Grinnell-1904 and Gaussian-1932

A

Evidence for interspecific competition

-give two species of paramecium and fixed amount of bacteria as food
-both showed logistic growth curve when separated but together one takes over the other

TWO SPECIES WITH THE SAME NICHE CANNOT COEXIST

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6
Q

If competitive exclusion is true, why are there so many species in the same habitat using the same resources?

A

habitat diversity

Grain beetles
Calandra beetle takes over the rhisopertha in 29.1C but in 32.3C Rhiso takes all resources

-temp is always changing maybe this is why they can coexist

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7
Q

Evidence for interspecific competition in nature?

A

1.Habitat shifts in allopathy and sympatry
2.Character displacement(ecological and reproductive)
3.Habitat differences and resource partitioning
4.Allelopathy

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8
Q

EVIDENCE OF INTERSPECIFIC

  1. Difference between allopathic and sympatric pop.
A

Allopatry= different home ( trout and char in separate lakes spread throughout)

Sympatry=same home( trout and char in same lake char only stays on bottom close to the shore and trout in center)

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9
Q

EVIDENCE OF INTERSPECIFIC

  1. What is character displacement?
A

the tendency for two species to diverge in form when in sympatry

ex. House Finch and black-headed Grosbeak -different size beaks b/c they live together

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10
Q

EVIDENCE OF INTERSPECIFIC

  1. What is the Hutchinson’s ratio?
A

Average Hutchinson’s ratio for sympatric species is 1.28
Mixed success in allying this

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11
Q

EVIDENCE OF INTERSPECIFIC

  1. Habitat differences and resource partitioning

-what is the ghost of competition past

A

It may look like there is competition but for example a forest how does all the different trees live in the same niche, they don’t have the same one. The roots under the soil take up different depths.

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12
Q

EVIDENCE FOR INTERSPECIFIC

  1. Habitat differences and resource partitioning

What is competition of the present?

A

-exotic species-artificial introducing a species into habitats they weren’t, leads to the displacement of native species that occupy similar habitats

ex. Scotch bloom introduced from Europe and now threatening native Garry Oaks

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13
Q

EVIDENCE OF INTERSPECIFIC
4. What is alleopathy?

What is Salvia?

What other things in ocean do this?

A

chemical competition in plants and animals
-the release of chemicals by on species in order to reduce growth or survivorship of another species

ex. Black walnut trees secrete Juglone from the roots
Crops like barley secretes alkaloids which reduces weeds

Salvia produces volatile terpines(bad smell)- two boxes with cucumber seeds- add Salvia to one doesn’t grow, b/c birds came to eat

Coral reefs- alleopathy among corals creating levels

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14
Q

Elton’s niche?

A

the role of a species in a community

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15
Q

Hutchinson’s niche?
What are the two niches in this?

A

-all biophysical conditions that characterize the life of a species

1-Fundamental niche
2-Realized niche

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16
Q

Fundamental vs realized niche

A

Fundamental- is the entire multidimensional space that represents the total range of condition within which an organism can function without limiting factors

Realized- the actual multidimensional space that a species can occupy taking into account biotic factors such as predators, competitors and parasites

17
Q

what is Lotka and Volterra competition model-1926

A

effect of species 2 on pop. growth of species 1

rN(K-N)-aN2/K

N2= pop. size of species 2

a=competition coefficient(alpha)
-if species 1=2. a=1

18
Q

What is biophagy?

A

consumption of bio material

19
Q

Survivorship Curves are largely due to..

A

predation

20
Q

What is the Functional response curves(FRC) measure?

A

rate of food consumption and density of prey

21
Q

What is Compensatory predation in FRC curve?

A

At low prey densities
a) reduced search efficiency
b) prey switching
c) search images(predator has a better image for more common prey)
d) aggregated responses of predators

22
Q

What is the threshold of security in a FRC curve

A

minimum density under which no further predation occurs

23
Q

What is the most important curve in FRC?

A

FRC #111- Multiple prey species eaten

24
Q

What age class do predators target?

A

mostly all predators target juveniles b/c of lowest cost of injury

-major exception to this trends is humans which target the largest

25
Q

Do predators limit maximum prey density?

A

Yes no. Predators don’t control prey density in long term. No statistical difference in numbers( Leibig’s law of minimum)

ex. took all predators out of forest no different long term

ex. Wolves keep caribou from exceeding K so yes they control density( if carrying capacity has been exceeded)

ex. Muskrats that didn’t have territories are killed more

No: if Leibig’s law of the minimum is acting
Yes: if carrying capacity has been exceeded
Yes: when native prey have no defenses against non-native predators

26
Q

Do predators limit maximum prey density?

Parasitic wasps(parasitoids)

A

important natural source of biological control of population numbers in insect host

wasp stings prey and control their movements into their burrow. Then wasp lays eggs, eggs eat organs for prey and make cocoon before breaking out

27
Q

Do predators limit maximum prey density?

Non-native predators preying on native or non-native species

A

No opportunity for co-evolution between them and natural equilibrium is disrupted

ex. Wild dogs(Dingos) preying on kangaroos. Dingos totally control density of kangaroos

28
Q

Relative abundance of predator and prey in a community

What are the ratios?

A

Endothermic predators(warm blood).- 1:300 ratio for predator to prey

Ectothermic predators( Relays on environment around them for body temp)- 60:300

29
Q

Exploitation rate of prey by each predator
species

A

Average 5% for each predator species

Biological interest= targets weak and young

Biological capital- reproductive adults (Humans do this)

30
Q

Defences of prey against predators-

First escape?

A

Camouflage or crysis

Conspicuous

31
Q

Defenses of prey against predators

Conspicuous, Why stand out?

Mullerian?
Batesian?

A

Warning(aposematic) colouration
-usually poisonous

Mullerian mimicry- when poisonous species mimic each other
Batesian mimicry- when a harmless species mimic a harmful one

32
Q

Defenses of prey against predators

What mechanism is the most frequent in arthropods(insects)?

A

Chemical

33
Q

Defence of plants against herbivores?

A

A) Plant structural defences -pointy
B)Plant chemical defences-odour,irritation,bitter(very common)

34
Q

Animal defences against plant chemical defenses.

A

a) mixed function oxidaze
b)concentration of toxins
c) selective browsing

Ecology midterm 2 (4 decks)

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